What Is ACE-031? Uses, Benefits, Safety, FDA Status, and Evidence
Medical review note: This article is for educational purposes only and does not provide medical advice. ACE-031 is not FDA-approved for human therapeutic use. Products sold online as ACE-031, ACVR2B-Fc, soluble activin receptor type IIB, myostatin inhibitor, muscle-growth peptide, bodybuilding peptide, or “research use only” ACE-031 may carry serious safety, quality, legal, and anti-doping risks.
Quick answer
ACE-031 is an investigational soluble activin receptor type IIB fusion protein. It was designed to bind and inhibit myostatin and other TGF-beta family ligands that normally limit muscle growth. ACE-031 increased lean body mass and thigh muscle volume in a single-dose human study and was tested in ambulatory boys with Duchenne muscular dystrophy. However, its Duchenne muscular dystrophy program was stopped early after safety findings including nosebleeds, gum bleeding, and visible dilated blood vessels called telangiectasias. ACE-031 is not FDA-approved, is not clinically available as a legitimate medication, and is prohibited in sport because WADA bans myostatin inhibitors.
Key facts about ACE-031
| Question | Answer |
|---|---|
| What is ACE-031? | An investigational soluble activin receptor type IIB fusion protein designed to inhibit myostatin and related ligands. |
| Other names | ACVR2B-Fc, ActRIIB-Fc, soluble activin type IIB receptor, ACE031, ACE-031 myostatin inhibitor. |
| Developer | Acceleron Pharma, later associated with Shire/Takeda development history. |
| Peptide/protein class | Myostatin inhibitor / soluble activin receptor type IIB fusion protein / TGF-beta superfamily ligand trap. |
| Main mechanism | Binds myostatin and other ligands that signal through activin receptor type IIB, reducing muscle-growth inhibitory signaling and potentially increasing skeletal muscle mass. |
| FDA-approved? | No. ACE-031 is not FDA-approved. |
| Main studied uses | Duchenne muscular dystrophy, muscle wasting, muscle growth, myostatin inhibition, lean-mass increase, and neuromuscular disease research. |
| Human evidence level | Limited and discontinued. Early studies showed lean-mass effects, but Duchenne development was stopped after safety concerns. |
| Animal/lab evidence level | Moderate to strong preclinical evidence for muscle-mass increases and ActRIIB-pathway biology. |
| Common online claims | “Myostatin blocker,” “muscle-growth peptide,” “bodybuilding peptide,” “lean-mass peptide,” “recovery peptide,” “DMD peptide,” “anti-aging muscle peptide.” |
| Sports status | Prohibited by WADA. WADA prohibits myostatin inhibitors, including agents that reduce or block myostatin signaling. |
| Main safety concern | Bleeding and vascular effects, including epistaxis, gum bleeding, and telangiectasias; broad TGF-beta ligand disruption; unknown long-term safety; product-quality risks; and anti-doping prohibition. |
What is ACE-031?
ACE-031 is a soluble activin receptor type IIB fusion protein. It was developed as a myostatin-pathway inhibitor to increase muscle mass and potentially improve muscle function in muscle-wasting diseases.
ACE-031 is not a typical short peptide. It is a larger biologic fusion protein built from the extracellular portion of activin receptor type IIB linked to an antibody Fc domain. This design lets ACE-031 act like a ligand trap.
A PubMed single ascending-dose study describes ACE-031 as a soluble form of activin receptor type IIB that promotes muscle growth by binding myostatin and other negative regulators of muscle mass.
A PubMed Duchenne muscular dystrophy study describes ACE-031 as a myostatin inhibitor tested in ambulatory boys with Duchenne muscular dystrophy.
The key distinction:
ACE-031 is a discontinued investigational biologic myostatin inhibitor, not an FDA-approved peptide, supplement, bodybuilding drug, or legal performance-enhancement product.
How does ACE-031 work?
ACE-031 works by blocking signaling from myostatin and related ligands.
Myostatin, also called GDF-8, is a natural protein that limits skeletal muscle growth. Blocking myostatin signaling can increase muscle mass in animals and humans.
ACE-031 binds ligands that signal through activin receptor type IIB, including:
- Myostatin / GDF-8
- Activins
- Some growth differentiation factors
- Other related TGF-beta family ligands depending on context
In plain English:
ACE-031 was designed to remove some of the biological brakes that limit muscle growth.
That is why it attracted interest for Duchenne muscular dystrophy and other muscle-wasting disorders.
But ACE-031 is broad. It does not only block myostatin. Its ActRIIB ligand-trap mechanism can affect other ligands involved in:
- Blood vessel biology
- Bone biology
- Reproductive signaling
- Inflammation
- Tissue remodeling
- Metabolism
- Developmental and repair pathways
That broader activity likely helps explain why safety issues emerged.
What is ACE-031 used for?
ACE-031 is investigational and discontinued. It is not approved for any use.
| Use | Evidence level | What is known | What is not known | |---|---|---| | Duchenne muscular dystrophy | Limited human evidence / discontinued | ACE-031 was tested in ambulatory boys with DMD and showed some muscle-related pharmacodynamic effects. | Development was stopped after safety findings, and it is not approved. | | Muscle growth / lean mass | Early human evidence | A single-dose study in healthy postmenopausal women showed increased lean body mass and thigh muscle volume. | Safe consumer muscle-building use is not established. | | Muscle wasting | Preclinical / investigational | ActRIIB blockade can increase muscle mass in models. | No approved ACE-031 treatment exists for cachexia, sarcopenia, or wasting. | | Bodybuilding | Unsupported and prohibited in sport | Myostatin inhibition can increase muscle mass biologically. | Consumer/bodybuilding use is unsafe, unapproved, and banned in sport. | | Sarcopenia / aging | Speculative | Myostatin inhibition is relevant to age-related muscle loss research. | ACE-031 is not an anti-aging or sarcopenia drug. | | Athletic performance | Unsupported and prohibited | Muscle-growth effects attract doping interest. | WADA prohibits myostatin inhibitors. | | Injury recovery | Unsupported | Online claims often extrapolate from muscle biology. | ACE-031 is not a recovery or tissue-healing medication. | | Online research-use ACE-031 | High risk | Sellers may market ACE-031-like products online. | Identity, purity, sterility, concentration, biologic activity, and legality may be unknown. |
What does the research show?
Human single-dose evidence
ACE-031 showed biological activity in an early human study.
A PubMed single ascending-dose study evaluated ACE-031 in healthy postmenopausal women. The study reported that ACE-031 increased lean body mass and thigh muscle volume after a single dose.
The practical interpretation:
ACE-031 can produce measurable lean-mass effects in humans, but early biological activity does not prove long-term safety or approved clinical value.
Duchenne muscular dystrophy evidence
ACE-031 was tested in boys with Duchenne muscular dystrophy.
A PubMed randomized placebo-controlled trial evaluated subcutaneous ACE-031 every 2 to 4 weeks in ambulatory boys with DMD.
The trial did not become an approved therapy. Development was stopped after vascular and bleeding-related safety findings.
The practical interpretation:
ACE-031 reached real human DMD testing, but the program failed to continue because safety concerns outweighed the development path.
Safety findings that stopped development
ACE-031’s development history is dominated by safety.
The Muscular Dystrophy Association reported that the ACE-031 Duchenne muscular dystrophy study was terminated and follow-on dosing was suspended after review of safety data with FDA and Health Canada. The reported safety findings included minor bleeding events and dilated blood vessels.
A review on myostatin targeting notes that Acceleron’s ACE-031 trial in boys with Duchenne muscular dystrophy was terminated early due to epistaxis and telangiectasias, likely related to ACE-031 binding BMP-9.
The practical interpretation:
The safety issue was not imaginary. ACE-031’s broad ActRIIB ligand-trap mechanism created vascular/bleeding signals that stopped clinical development.
Preclinical muscle evidence
ACE-031 and related soluble ActRIIB approaches have strong preclinical muscle-growth evidence.
A PMC preclinical study reported that administration of a soluble activin type IIB receptor promoted skeletal muscle growth. Later preclinical work also examined ACE-031 in muscular dystrophy models.
The practical interpretation:
Preclinical muscle growth is real, but the clinical problem is safety, selectivity, and translation.
Why ACE-031 is different from simple myostatin antibodies
ACE-031 is broader than a myostatin-only antibody.
It is an ActRIIB ligand trap, so it can bind multiple ligands. That broad activity may increase muscle more strongly than myostatin-only inhibition, but it may also increase unwanted effects.
This is the core tradeoff:
| Strategy | Potential advantage | Potential problem |
|---|---|---|
| Myostatin-only antibody | More selective | May produce weaker muscle effects. |
| ActRIIB ligand trap like ACE-031 | Broader and potentially stronger muscle effects | Higher risk of off-target ligand disruption, including vascular effects. |
The practical interpretation:
ACE-031’s strength was also its weakness. It blocked more than myostatin.
Evidence summary
| Claim | Evidence verdict | Explanation |
|---|---|---|
| “ACE-031 is a myostatin inhibitor.” | Supported | ACE-031 binds myostatin and related ActRIIB ligands. |
| “ACE-031 is a soluble activin receptor type IIB fusion protein.” | Supported | It is commonly described as soluble ActRIIB-Fc. |
| “ACE-031 increases lean mass.” | Supported in early human evidence | A single-dose study reported increased lean body mass and thigh muscle volume. |
| “ACE-031 treats Duchenne muscular dystrophy.” | False as an approved claim | It was tested in DMD but is not approved and development stopped. |
| “ACE-031 is FDA-approved.” | False | No FDA-approved ACE-031 product exists. |
| “ACE-031 is safe for bodybuilding.” | False | Safety was a major problem in clinical development, and bodybuilding use is unapproved. |
| “ACE-031 caused bleeding and vascular issues in trials.” | Supported | Reported issues included epistaxis, gum bleeding, and telangiectasias. |
| “ACE-031 is allowed in sport.” | False | WADA prohibits myostatin inhibitors. |
| “ACE-031 is just like follistatin.” | False | Both can inhibit myostatin signaling, but ACE-031 is a soluble ActRIIB-Fc ligand trap. |
| “Research-use ACE-031 is clinically proven.” | False | Research-use products are not FDA-approved consumer therapeutic products. |
Is ACE-031 FDA-approved?
No. ACE-031 is not FDA-approved.
There is no FDA-approved ACE-031 product for:
- Duchenne muscular dystrophy
- Becker muscular dystrophy
- Muscle growth
- Bodybuilding
- Sarcopenia
- Cachexia
- Fat loss
- Body recomposition
- Injury recovery
- Anti-aging
- Athletic performance
- Any human therapeutic use
The key distinction:
ACE-031 was a clinical-stage investigational biologic, but it did not become an approved drug.
Is ACE-031 legal?
ACE-031’s legal status depends on country, product type, intended use, and whether it is part of an authorized clinical trial.
For U.S. readers:
ACE-031 is not an FDA-approved drug, and online availability does not mean it is legally marketed for human therapeutic or enhancement use.
Some sellers market ACE-031 as a research peptide, muscle-growth peptide, myostatin inhibitor, bodybuilding compound, or performance-enhancement product. That does not make it safe, approved, legal, or appropriate for consumer use.
The blunt version:
Buying “research use only” ACE-031 online is not the same as receiving an FDA-approved prescription medication or regulated biologic therapy.
Is ACE-031 banned in sports?
Yes. ACE-031 is prohibited in sport.
WADA prohibits myostatin inhibitors, including substances that reduce or block myostatin expression or activity. ACE-031 is a myostatin-pathway inhibitor and falls directly into this prohibited category.
The practical advice:
Athletes subject to anti-doping rules should not use ACE-031, ActRIIB-Fc products, myostatin inhibitors, follistatin-like products, or related muscle-growth biologics.
Safety and side effects
ACE-031 should be treated as high risk.
Reported or plausible risks include:
- Nosebleeds
- Gum bleeding
- Telangiectasias
- Dilated superficial blood vessels
- Vascular effects
- Injection-site reactions
- Immune or allergic reactions
- Unknown long-term safety
- Broad TGF-beta ligand disruption
- Reproductive/endocrine pathway effects
- Bone and tissue-remodeling uncertainty
- Possible effects from BMP-9/BMP-10-related vascular biology
- Tumor-biology uncertainty
- Product mislabeling
- Contamination
- Incorrect protein identity or concentration
- Sterility and endotoxin risks
- Anti-doping violations
The biggest issue is the mechanism.
ACE-031 does not only block myostatin. It can affect multiple ligands that matter in blood vessels, tissue remodeling, and endocrine biology.
That is why the online “muscle peptide” framing is dangerously incomplete.
ACE-031 vs similar peptides, proteins, and drugs
| Compound | Category | Main difference |
|---|---|---|
| ACE-031 | Soluble activin receptor type IIB fusion protein | Broad ActRIIB ligand trap; inhibits myostatin and related ligands; discontinued after safety concerns. |
| Follistatin-344 | Follistatin gene/transcript form | Inhibits myostatin and activin through follistatin biology; gene-transfer research focus. |
| Myostatin / GDF-8 | Muscle-growth inhibitor | Natural brake on muscle growth; ACE-031 blocks its signaling. |
| Bimagrumab | Activin receptor antibody | Targets activin receptors differently; studied for muscle/metabolic disease. |
| Stamulumab / MYO-029 | Anti-myostatin antibody | More myostatin-selective antibody approach; not the same as ACE-031. |
| Domagrozumab | Anti-myostatin antibody | Myostatin-targeting antibody studied in DMD; different mechanism. |
| Apamorelin / ACE-083 | Locally acting myostatin-pathway inhibitor | Related development lineage but different product and use concept. |
| Follistatin | Myostatin/activin-binding protein | Naturally occurring protein and gene-therapy strategy, not ActRIIB-Fc. |
| IGF-1 LR3 | Growth-factor analog | Growth-factor pathway, not myostatin inhibition. |
| Growth hormone secretagogues | GH-axis peptides | Increase GH signaling indirectly; different pathway and risk profile. |
The key distinction:
ACE-031 belongs in the myostatin/activin pathway inhibitor category. It is not a generic peptide, not a supplement, and not an approved muscle-building drug.
Why is ACE-031 sold as “research use only”?
Some online sellers use “research use only” language to sell ACE-031 outside normal drug channels.
That label is not a trust signal.
A serious reader should understand this distinction:
| Product type | What it means |
|---|---|
| Clinical-trial ACE-031 | Investigational biologic used under monitored research protocols. |
| FDA-approved ACE-031 | Does not currently exist. |
| Research-use ACE-031 | Not an FDA-approved consumer therapeutic product. |
| Online ACE-031 vial | High risk for identity, purity, sterility, concentration, biologic activity, and safety problems. |
| Myostatin-inhibitor bodybuilding product | Unapproved and prohibited in sport. |
How to evaluate ACE-031 claims online
| Claim | What to verify |
|---|---|
| “FDA-approved ACE-031” | False. ACE-031 is not FDA-approved. |
| “Clinically proven muscle-growth peptide” | Misleading. Early lean-mass effects exist, but no approved consumer or therapeutic use exists. |
| “Safe myostatin blocker” | False. Development stopped after vascular and bleeding-related safety findings. |
| “Treats Duchenne muscular dystrophy” | False as an approved claim. DMD studies occurred, but ACE-031 is not approved. |
| “Legal for athletes” | False. WADA prohibits myostatin inhibitors. |
| “Same as follistatin” | False. ACE-031 is a soluble ActRIIB-Fc ligand trap, not follistatin. |
| “No side effects” | False. Epistaxis, gum bleeding, and telangiectasias were reported in development. |
| “Research use only” | This does not mean safe, legal, approved, or appropriate for human use. |
| “Builds muscle without risk” | Unsupported and reckless. |
| “Third-party tested” | Ask for batch-specific identity, purity, LC-MS, HPLC, sterility, endotoxin, microbial, and stability data. |
| “Gene-doping safe alternative” | False. Myostatin inhibition is an anti-doping concern. |
Bottom line
ACE-031 is an investigational soluble activin receptor type IIB fusion protein designed to inhibit myostatin and related ligands. It showed real muscle-mass biological activity in early human research and was studied in Duchenne muscular dystrophy.
The most defensible conclusion is:
ACE-031 is a discontinued experimental myostatin inhibitor, not a safe or approved muscle-building peptide. It is not FDA-approved, its development was stopped after vascular and bleeding-related safety concerns, online products are high risk, and WADA prohibits myostatin inhibitors in sport.
FAQ
What is ACE-031?
ACE-031 is an investigational soluble activin receptor type IIB fusion protein designed to bind and inhibit myostatin and related ligands involved in limiting muscle growth.
What does ACE-031 do?
ACE-031 blocks signaling from myostatin and other ActRIIB ligands, which can reduce muscle-growth inhibition and increase lean mass in studied settings.
Is ACE-031 FDA-approved?
No. ACE-031 is not FDA-approved for Duchenne muscular dystrophy, muscle growth, bodybuilding, sarcopenia, anti-aging, recovery, or any other use.
Is ACE-031 a peptide?
ACE-031 is better described as a biologic fusion protein, not a simple short peptide. It is a soluble activin receptor type IIB-Fc ligand trap.
Is ACE-031 a myostatin inhibitor?
Yes. ACE-031 inhibits myostatin signaling, but it can also bind other related ligands, making it broader than a myostatin-only inhibitor.
Does ACE-031 build muscle?
Early human research showed increased lean body mass and thigh muscle volume after a single dose, and preclinical studies support muscle-growth effects. That does not make ACE-031 safe, approved, or appropriate for consumer use.
Was ACE-031 studied for Duchenne muscular dystrophy?
Yes. ACE-031 was tested in ambulatory boys with Duchenne muscular dystrophy, but development was stopped after safety findings.
Why was ACE-031 discontinued?
ACE-031 development was stopped after safety findings including bleeding events and telangiectasias. Reviews suggest this may have related to broader ligand binding, including BMP-9-related vascular biology.
Is ACE-031 safe?
No reliable basis exists to call ACE-031 safe for consumer use. Reported concerns include nosebleeds, gum bleeding, telangiectasias, vascular effects, immune reactions, unknown long-term safety, and product-quality risks.
Is ACE-031 the same as follistatin?
No. Both can inhibit myostatin-related biology, but ACE-031 is a soluble activin receptor type IIB fusion protein. Follistatin is a separate myostatin/activin-binding protein.
Is ACE-031 legal?
ACE-031 is not an FDA-approved drug. Online sale as a research product does not mean it is legally marketed for human therapeutic or enhancement use.
Is ACE-031 banned in sports?
Yes. WADA prohibits myostatin inhibitors. ACE-031 is a myostatin-pathway inhibitor and should be considered prohibited for athletes subject to anti-doping rules.
Why do sellers call ACE-031 “research use only”?
Sellers often use “research use only” language because ACE-031 is not FDA-approved for consumer therapeutic use. The phrase does not make the product safe, legal, approved, or clinically proven.
What is the biggest risk with ACE-031?
The biggest risks are using an unapproved broad myostatin/activin-pathway inhibitor without adequate safety data, ignoring the vascular and bleeding findings that stopped development, buying mislabeled online products, and violating anti-doping rules.
Sources
- PubMed: A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers
- PubMed: Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy
- Wiley: Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy
- ClinicalTrials.gov: Study of ACE-031 in Subjects With Duchenne Muscular Dystrophy
- MDA: Update: ACE-031 Clinical Trials in Duchenne MD
- PMC: Administration of a soluble activin type IIB receptor promotes skeletal muscle growth
- PubMed: ACE-031, a soluble activin type IIB receptor, increases muscle weight and strength in muscular dystrophy models
- PMC: ACE-031, a soluble activin type IIB receptor, increases muscle weight and strength in muscular dystrophy models
- Oxford Academic: Challenges and Future Prospects of Targeting Myostatin Signaling
- Johns Hopkins: ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy
- WADA: Prohibited List
- WADA: 2026 Prohibited List PDF
- USADA: WADA Prohibited List Guidance
Frequently asked questions
What is ACE-031?
ACE-031 is an investigational soluble activin receptor type IIB fusion protein designed to bind and inhibit myostatin and related ligands involved in limiting muscle growth.
What does ACE-031 do?
ACE-031 blocks signaling from myostatin and other ActRIIB ligands, which can reduce muscle-growth inhibition and increase lean mass in studied settings.
Is ACE-031 FDA-approved?
No. ACE-031 is not FDA-approved for Duchenne muscular dystrophy, muscle growth, bodybuilding, sarcopenia, anti-aging, recovery, or any other use.
Is ACE-031 a peptide?
ACE-031 is better described as a biologic fusion protein, not a simple short peptide. It is a soluble activin receptor type IIB-Fc ligand trap.
Is ACE-031 a myostatin inhibitor?
Yes. ACE-031 inhibits myostatin signaling, but it can also bind other related ligands, making it broader than a myostatin-only inhibitor.
Does ACE-031 build muscle?
Early human research showed increased lean body mass and thigh muscle volume after a single dose, and preclinical studies support muscle-growth effects. That does not make ACE-031 safe, approved, or appropriate for consumer use.
Was ACE-031 studied for Duchenne muscular dystrophy?
Yes. ACE-031 was tested in ambulatory boys with Duchenne muscular dystrophy, but development was stopped after safety findings.
Why was ACE-031 discontinued?
ACE-031 development was stopped after safety findings including bleeding events and telangiectasias. Reviews suggest this may have related to broader ligand binding, including BMP-9-related vascular biology.
Is ACE-031 safe?
No reliable basis exists to call ACE-031 safe for consumer use. Reported concerns include nosebleeds, gum bleeding, telangiectasias, vascular effects, immune reactions, unknown long-term safety, and product-quality risks.
Is ACE-031 banned in sports?
Yes. WADA prohibits myostatin inhibitors. ACE-031 is a myostatin-pathway inhibitor and should be considered prohibited for athletes subject to anti-doping rules.
Sources
- [1]
- [2]
- [3]
- [4]
- [5]MDA: Update: ACE-031 Clinical Trials in Duchenne MD
Patient Advocacy Update
- [6]
- [7]
- [8]
- [9]
- [10]
- [11]WADA: Prohibited List
Anti Doping
- [12]WADA: 2026 Prohibited List PDF
Anti Doping
- [13]USADA: WADA Prohibited List Guidance
Anti Doping
Last updated May 9, 2026